Multilayer Reflective Film Outer Periphery Composition for EUV Mask
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Solution Overview
Problem
The existing reflective mask blanks for EUV lithography suffer from film peeling issues in the multilayer reflective film during cleaning processes, leading to pattern defects due to the high compressive stress in silicide films with high Si content, which are not adequately addressed by the modified areas in prior substrates.
Innovation Solution
A substrate with a multilayer reflective film where the outermost periphery is formed as a compound of silicon and a transition metal, with a Si to total metal atomic ratio of 0.50 or less, and optionally containing oxygen, to reduce compressive stress and enhance chemical resistance, thereby preventing film peeling and defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the multilayer reflective film is formed using conventional sputtering methods with high Si content silicide films, then the reflectivity for EUV light is improved, but film peeling occurs during cleaning processes due to high compressive stress
Solution Approach 1:
The patent changes the compositional parameters of the outermost layer by controlling the Si to transition metal atomic ratio to be 0.50 or less, and introducing oxygen content of 0.5-75 atomic %. This parameter optimization reduces compressive stress while maintaining EUV reflectivity, preventing film peeling during cleaning processes
Solution Approach 2:
The patent creates a composite material structure in the outermost layer combining silicon, transition metal (Mo, Ru, Rh, or Pt), and oxygen. This composite composition forms a compound that balances optical performance with mechanical stability, reducing film stress and improving adhesion reliability
2Illumination intensity
If the outermost layer has high Si content to improve EUV reflectivity, then the optical performance is enhanced, but chemical resistance during cleaning processes deteriorates
Solution Approach 1:
The patent optimizes the chemical composition parameters by limiting Si content relative to transition metal (Si/(Si+TM) ≤ 0.50) and adding controlled oxygen (0.5-75 atomic %). This compositional adjustment enhances chemical resistance to cleaning solutions while preserving sufficient EUV reflectivity
3Reliability
If a modified area is formed in the outer peripheral area of the multilayer reflective film, then film peeling is reduced, but the compressive stress in high Si content silicide films remains high causing defects
Solution Approach 1:
The patent applies local quality modification by creating a distinct outermost layer with specific compositional characteristics (low Si/TM ratio and controlled oxygen content) different from the inner multilayer structure. This localized compositional optimization reduces compressive stress at the film periphery where peeling is most likely, while maintaining overall pattern transfer accuracy
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively prevents film peeling and reduces defects in the multilayer reflective film and absorber film, improving pattern transfer accuracy and chemical resistance during mask manufacturing and use.
Implementation Method 1
a multilayer reflective film for reflecting exposure light formed on a substrate
Implementation Method 2
layers containing elements having different refractive indices are periodically layered
Implementation Method 3
an absorber pattern which is a patterned absorber film formed on the multilayer reflective film for absorbing exposure light
Implementation Method 4
The multilayer reflective film is usually formed on a main surface of a substrate using an ion beam sputtering device or a magnetron sputtering device
Implementation Method 5
The Multilayer reflective film is usually formed on a main surface of a substrate using an ion beam sputtering device or a magnetron sputtering device
Data Source
AI summary
A substrate with a multilayer reflective film, a reflective mask blank, a method for manufacturing a reflective mask, and a method for manufacturing a semiconductor device capable of preventing film peeling of a multilayer reflective film due to cleaning or the like during a mask manufacturing process and use of a mask, and reducing occurrence of defects on an absorber film due to the film peeling of the multilayer reflective film.